Dilatometer



H. RIEPERT DILATOMETER Jan. 3, 1939.

Fi led Jan. 22, 1938 INVENTOR O llama/1111?:

Patented Jan. 3, 1-939 DILATOMETEB Hermann ltiepert, Wetzlar, assignmto Ernst Leitz', G. in. b. 11., Wetzlar, Germany Application January 22, 1938. Serial No. 188,44)? In Germany February 15, 1937 2 Claims.

'Ihis invention relates to improvements in dilatometers which are used for determining and recording in a system of coordinates the behavior of metals when subjected to a variation in temperature independent of a standard body. Such dilatometers include supporting means for the specimen to be tested, the usual measuring bridge, a mirror galvanometer and an optical system for translating'the movements or the specimen and the movements of the mirror of the galvanometer by means of a pencil light into a photographic record upon a light sensitive surface in the form of an expansion temperature curve. The apparatus includes a removable oven for heating the specimen and a tank containing cooling liquid for the purpose of quenching the specimen. In order to perform the quenching in a practical manner and without loss of time, the apparatus is mounted so as to be tipped orinclined to immerse the specimen into the cooling liquid. The galvanom- 'eter is connected to a thermo couple which is inserted in the specimen,

In operation the specimen is heated in a removable oven and thereafter immersed in a cooling liquid. The operation is performed by moving the oven away from the specimen which thereafter is tipped for immersion. The entire dilatometer is'tipped or inclined and it has been found that with an ordinary mirror galvanometer inaccuracies and variations in the path of* light occurs when the apparatus is tipped in that the mirror and coil Swing away from the magnet so thatlthe luminous point on the sensitive surface is moved to such an extent that the measurement curves cannot be depended upon.

The object of the invention is to eliminate such disadvantage by employing a string galvanometer of the DArsonval type in which the mirror is capable of being inclined together with the dilatometer whereby to eliminate and variations.

Accordingly the invention is embodied in a dilatometer arranged and constructed as hereinafter set forth and as illustrated in the accomsuch inaccuracies panying'drawing.

The apparatus consists of a dilatometer I which is mounted upon a tiltable base I pivoted. at 8 upon a base 6. Upon the base is suitably mounted a photographic camera .5 which includes a source of light ,a-refiecting mirror i3, a string mirror galvanometer l0 and the usual well known measuring bridge 23 which includes the reflecting tiltable element l2. s

The measuring bridge 23 is actuated as usual by a steering rod 22 which in turn is moved by the (Cl. 73-51) v expansion of the specimen rod 8. In the latter there is inserted a thermo couple 2 connected to the galvanometer by wires as shown.

The dilatometer is tilted or inclined as shown in I order to quench the specimen in a-cooling liquid 5 contained in the cooling tank 9. The oven for heating the specimen is indicated at I and runs on the base on rollers It so that it is readily removable from the specimen.

The galvanometer is of the type known as a string galvanometer of the D'Arsonval type. It comprises a suitable support 25 for the permanent horseshoe magnet I 0 within which the coil l8 and the mirror H is held by a string I9 which is securedas at and 2|. A carrier ll connects the mirror and the galvanometer coil. The galvanorneter therefore is characterized by the ,fact that the mirror is capable only of rotatable movement in a horizontal plane or a plane parallel to the axis of the camera and is not tiltable in relation to the dilatometer.

.In operation the dilatometer is placed in horizontal operative position upon the base 8 and the oven moved in over the specimen. When the specimen has been heated to a certain predetermined high temperature, the oven is moved away. as shown so that the dilatometer may be inclined and the specimen quenched in the cooling tank.

The specimen is in known manner enclosed in a quartz tube and as it expands it moves the steering rod 22 which in turn actuates the measuring bridge so that the tiltable reflector i2 is moved on its axis which is fixed. The light my from the .lamp Ii strikes the reflector l2 and is by the latter reflected into the mirror M of the string galvanometer.

Because of the current created by the thermo v a the camera is provided with a suitable sensitive medium l5 for receiving and photographing the path of the light beam. The principles underlying the general construction and operation of dilatometers are Well known in the art and have therefore not been described in detail herein. The feature of the invention resides in the use of a galvanometrically actuated mirror which is swingable in a plane parallel to the camera axis but non-tiltable in relation thereto.

1. In a dilatometer for measuring and recording' in a system of coordinates the temperature variations in a specimen to be tested including a base, an oven and a quenching tank below the same, a pivot for supporting the dilatometer upon the base tomove the dilatometer from a horizontal specimen heating position in said oven to an angular specimen quenching position within the said tank, a galvanometer and .a thermo couple in the specimen connected to the galvanometer, an optical dilatometer system, a mirror in said system for translating the movements 0! photcgraphically recorded expansion temperature curve and means connecting the galvanometer coil and the said mirror to impart to the latter a swingable movement in response to the movements oi! the galvanometer coil in only one plane parallel to the horizontal plane through the axis of the said pivot.

.2. A dilatometer according to claim 1 characterized by that the galvanometer is a string mirror galvanometer.

' I HERMANN RIEPERT.

the specimen and of the galvanometer coil into a V 

